Telephone-exchange system.



L. H. JOHNSON.

TELEPHONE EXCHANGE SYSTEM.

APPLICATIONIFILED MAY 26. I916.

Patented Jan. 2,1917.

1n: narems versus ca. Pnamuma. wAsnmcmm vided with barren s rarns ra rnnr errron LEWIS I-I. JOHNSON, F BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented J an. 2, 191 7.

To all whom it may concern:

Be it known that I, Lnwrs H. JOHNSON, a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems of which an operators telephone set is automatically connected i to and disconnected from a calling telephone line.

The object of this invention is the provision of means for increasing the efiiciency of the operators of a telephone exchange and for facilitating the completing of connections between subscribers.

In accordance with this invention, a telephone exchange system, in which the operators telephone set is automatically'connected to a calling telephone line upon the connection of a link circuit therewith, is procircuits and apparatus so organized that, while the operators telephone set is connected to one calling telephone line, it I cannot be connected to any other calling line, but a second connection may be pre-v pared during the existence of the first so that upon the disconnection telephone set from the first calling line, it will be immediately connected to the calling line forming a part of the prepared connection.

This invention is an improvement on that disclosed in the application of Henry P. Clausen, Ser. No. 59,972, filed November 6,

1915, in that less apparatus is required for accomplishing the desired result.

More specifically this invention contemplates a telephone exchange system in which there are link circuits for interconnecting subscribers lines and a relay associated with each link circuit operating upon connection of the link circuit with a calling subscribers line to include an operators telephone set in circuit therewith, the operation of any one listening relay establishing a short circuit for all other listening relays of that position, whereby an operator is prevented from being connected to more than one line at the same time.

This invention is illustrated in the accompanying drawing, in which there are shown the central energy type in of the operators ordinary subscribers lines A, B, C, and D (lines B, G and D being indicated merely by the jacks thereof) and cord circuits E and F for interconnecting the subscribers lines. The apparatus of each cord circuit is exactly alike, and the same reference characters will be used in each to indicate the same apparatus.

Assuming that subscriber A wishes to converse with subscriber B, A will signal the central office in the usual manner, whereupon the operator will insert the answering plug of the cord circuit E in the jack associated with As line, causing the operation of sleeve relay and supervisory relay 6. The operation of supervisory relay 6 causes the operation of listening relay 7 over a circuit from battery, through resistance 8, common conductor 9, contact 10 of relay 7 contact 11 of relay 12, winding of relay 7, alternate contact of relay 6 and supervisory lamp 13 to ground. Listening relay 7, in operating, connects an operators telephone set 15 across the talking strands of cord circuit E, and completes a locking circuit for itself from battery, through contact16 of relay 7, contact 11 of relay 12, winding of relay 7 alternate contact of relay 6 and supervisory lamp 13 to ground. Contact 16 of relay 7 makes before contact 10 breaks, so that the circuit of relay 7 remains closed. The operation of relay 7 also closes its contact 17, which puts a direct ground on the common conductor 9 and short-circuits the listening relays of all other cord circuits in that position. The operator, finding the desired number to be that of subscriber B, completes the connection by inserting the calling plug of the cord circuit E into the jack associated with Bs line, causing the operation of relay 12, which opens the locking circuit of relay 7, permitting it to release and causes the lighting of supervisory lamp 20. The release of listening relay 7 of cord circuit E disconnects the operators telephone set from this cord circuit and opens its contact 17, removing the short circuit of all other listening relays in that position. The operator actuates ringing key 21 to send ringing current over Bs line to operate the call bell thereat. Subscriber B, in responding, removes the receiver from the switchhook, causing the operation of supervisory relay 22 to efl'ace supervisory lamp 20. When conversation is completed, both subscribers restore the receivers to the switchhooks, causing the light- 111g f s pervi y a p 1 31 2 t u nish disconnect signals, whereupon the operator removes both plugs from the jacks, restoring all apparatus to normal. a

While the operator was busy completing connections between subscribers A and B,

and before the calling plug of the cord circuit E was inserted into the jack of 'Bs line, subscriber Cmay have called The operatorcould take "up this call by inserting the answering plug of "cord circuit jF into the ja f G'vs li Bclays an fi q circuit F be operated, butthe listening relay"? hereof w 1 cause of the short circuitof this relay'm'aintamed by theactuated condition of listening relay 7 in cord circuit E. As s oon, however, as the operator c'onipletesfthe establishment of connection betwcen lines A and relay 7 of the cord circuit E will be're- I leased, I as hereinbefor'e described, thereby removing the short circuit of the listening relay 7 of cord circuitIf, "which thereupon operates over a circuit "similar 'to that describcd for relay 7 "of cord circuit 15. The

operation of this relay of cordcircuit F establ'ish'es"a short circuitj for the listening elayslof all other cord'circuitsin tha 1p sition, including the relay 7 ofcord circuit The connections between lines C and D may be completed in thesame manner as described in connection with the establishment of connections between lines A 'arfdB.

copi es cf this patent 'iiiayie dammed forfive cents Each; byaddrssing the It will be noted from the drawing and fromthe above description that this invencan 'provid'es simplifie'd means for increasan operators telephone set, a relay associatedwith each link circuit operating upon connection thereof with a'calling line t'o i'n'clude thecperator s telephone'set in. circuit therewith, and a short circuit for allother relays established up on the cnergization of one i of the relays, whereby the operatofis telephone set can be connected'to only one line at a time. 7 p 7' H I :2. II1 a telephoneexchange system, subscribers lines terminating at 'a central bfiice,

link circuits for interconnecting said lines,

an operators telephone 'set, a relay "assoc1ate"c l'w1th each lmk circuit operatmg upon connection thereof'with a callingline to includethe operators telephone set-"incircuit therewith, and a normally open circuit multipled to each ofthe "relays completed by thebp e ration or anyone of the relays to es tablish a short circuit 'of all other relays.

I p In witness whereofl'l hereunto subscribe my name this 24th day of May, A. D. 1916.

LEWIS H. JOHNSON.

coihmissianer' of Patents,

' Washington; "110. 

